U.S. Pat. No. 2,538,403 discloses a compression extractor. This compression extractor comprises a lower tank portion and an upper tank portion, which together form a tank chamber. The upper tank portion has perforated walls and an opening for receiving the material from which liquid is to be extracted. Clamped between the upper tank portion and the lower tank portion is a pressure-actuated membrane. A pressure medium is introduced into the lower tank portion to compress the membrane against the material in the upper tank portion to extract the liquid therefrom. The liquid is collected from the upper tank portion through the perforations in the walls of the upper tank portion. The upper tank portion also includes means for discharging the leftover solid material remaining after the liquid has been extracted.
A second compression extractor is disclosed in German Pat. No. 2,456,247. This compression extractor includes a cylindrical tank which is divided by an elastic membrane into two chambers. Material, such as fruit mash, containing liquid to be extracted, is introduced into the first chamber. A pressure medium is introduced into the second chamber to press the membrane against the liquid containing material in the first chamber so as to extract the liquid therefrom. A liquid collection system is provided in the first chamber to remove the extracted liquid.
In both of the above-described compression extractors, extracted liquid located near the liquid collection system is satisfactorily removed from the compression extractor. However, extracted liquid located near the membrane is not satisfactorily removed from the extractor, as no means for carrying off the liquid is provided in this region and the essentially smooth membrane hinders drainage.
The object of the present invention is to create a device in which this defect is eliminated and which therefore enables more efficient deliquification of the mash.